In order to allow high breakdown voltage, low loss, usage under a high temperature environment and the like for semiconductor devices, the usage of silicon carbide is continuing to advance in recent years as the material for forming semiconductor devices. Silicon carbide is a wide band gap semiconductor having a band gap greater than silicon that is conventionally used widely as a material forming semiconductor devices. The usage of silicon carbide as the material forming a semiconductor device allows high breakdown voltage, reduction in ON resistance and the like of semiconductor devices. Furthermore, a semiconductor device based on silicon carbide material is advantageous in that degradation in the property, when used under a high temperature environment, is small as compared to a semiconductor device based on carbide material.
For semiconductor devices controlling the formation of an inversion layer at a channel region in accordance with a predetermined threshold voltage to pass and cut off current such as an MOSFET (Metal Oxide Semiconductor Field Effect Transistor) and IGBT (Insulated Gate Bipolar Transistor), among semiconductor devices employing silicon carbide as the material, various approaches have been made to reduce ON resistance while suppressing resistance in the channel region (for example, refer to Japanese Patent Laying-Open No. 2007-80971 (PTL 1) and Japanese Patent Laying-Open No. 2002-261095 (PTL 2)).